Stimulus dimension shifts in patients with schizophrenia, with and without paranoid hallucinatory symptoms, or obsessive compulsive disorder: strategies, blocking and monoamine status

Abstract

Reversal, and intra-dimensional (ID) and extra-dimensional (ED) nonreversal discrimination shifts were studied to see if learned inattention to the irrelevant dimension differentially influenced the efficacy of learning and stimulus choice strategy. Performance was compared with conditioned blocking (CB) and monoamine metabolic status between healthy controls, patients with obsessive compulsive disorder (OCD) or schizophrenia with (PH) or without (NP) active paranoid hallucinatory symptoms. PH and NP patients improved learning with practice, but showed an impaired shift on each task. OCD patients were impaired only on the ED-shift. The NP patient's impairment was nonspecific and, unlike PH and controls, it related to reversal performance. All subjects acquired an attentional set for colour reflected in the length of stimulus-response sequences. Analysis of paired-stimulus choice-strategies showed that while all patients showed fewer correct win-stay choices, only PH patients perseverated with lose-stay choices. Learning about the added stimulus in the CB task related to ID-shift efficiency in NP patients. Increases of dopamine activity related to delayed learning but more switches of stimulus choice in the shift-tasks. Increases of serotonin activity correlated with faster learning in controls, OCD and PH patients. In NP patients the opposite held for dopamine and serotonin activity. Thus the two learned inattention tasks have different if related requirements and correlates: the data are consistent with the use of automatic exogenous attention strategies by NP patients, of inefficient controlled attention by PH patients and the automatization of endogenous processes in controls.

Prefrontal Serotonin Depletion Affects Reversal Learning But Not Attentional Set Shifting

“…Together, these data demonstrate that prefrontal 5-HT is not important for higher-order shifting of attention, despite being critical for behavioral flexibility at the level of responding to altered stimulus-reward contingencies, highlighting the differential sensitivity of distinct prefrontal cognitive functions to serotonergic modulation. The mild impairment of 5-HT-lesioned animals on the distractor test may reflect a more general role for 5-HT in stimulus salience, as proposed by Oades (1997). In addition, these data extend our previous findings on discrimination reversal learning in which the deficit was not apparent until the second reversal (Clarke et al, 2004) and illustrate that the deficit can be observed on the first reversal.…”

Mechanisms Underlying Motivational Deficits in Psychopathology: Similarities and Differences in Depression and Schizophrenia

“…Such an interpretation would predict that individuals with schizophrenia would show deficits on reinforcement learning tasks that also tap into these mechanisms. However, the evidence suggests surprisingly intact performance on a range of tasks in which learning is either relatively easy or relatively implicit (Elliott et al 1995;Hutton et al 1998;Joyce et al 2002;Turner et al 2004;Tyson et al 2004;Jazbec et al 2007;Waltz and Gold 2007;Ceaser et al 2008;Heerey et al 2008;Weiler et al 2009;Somlai et al 2011), though with some exceptions (Oades 1997;Pantelis et al 1999). Further, individuals with schizophrenia show intact learning rates on the weather prediction task, a probabilistic category-learning task frequently used to measure reinforcement learning, though with overall impaired performance (Keri et al 2000(Keri et al , 2005aWeickert et al 2002Weickert et al , 2009Beninger et al 2003).…”

“…In addition, several studies suggest impaired reversal learning in schizophrenia (Elliott et al 1995;Oades 1997;Pantelis et al 1999;Tyson et al 2004;Turnbull et al 2006;Waltz and Gold 2007;Ceaser et al 2008), though a few studies using the intra-dimensional/extradimensional task did not find simple reversal learning deficits in schizophrenia (Hutton et al 1998;Joyce et al 2002;Jazbec et al 2007). These reversal learning impairments are present even when individuals with schizophrenia and controls are matched on initial acquisition performance (Weiler et al 2009).…”

Goal Representations and Motivational Drive in Schizophrenia: The Role of Prefrontal-Striatal Interactions

“…Yet surprisingly, a large number of studies have suggested intact reinforcement learning in schizophrenia using a range of tasks in which learning is relatively easy, [125][126][127][128][129][130][131][132][133][134] though with a few exceptions. 135,136 In contrast, when the paradigms become more difficult and include varying levels of probability and discrimination, individuals with schizophrenia show more evidence of impaired reinforcement learning. 137,138 For example, Gold and colleagues 139 found evidence for impaired learning in schizophrenia on the Frank Probabilistic Discrimination Task.…”

“…Both require individuals to integrate information about rewards and punishments across trials and to use such information to update value representations appropriately. A number of studies suggest impaired reversal learning in schizophrenia, 125,130,131,133,135,136,154 though a few studies using the Intra-Dimensional-Extra-Dimensional task did not find simple reversal learning deficits in schizophrenia. [127][128][129] These reversal learning impairments are present even when individuals with schizophrenia and controls are matched on initial acquisition performance.…”